(1) Field of the Invention
The present invention relates to an electronic document management device and the like, and specifically to a management device and the like that manage the security of electronic documents.
(2) Description of the Related Art
In recent years, as an increasing number of image forming apparatuses have become multi-functional to have functions such as scanning, copying, printing, and faxing, there have appeared image forming apparatuses equipped with a storage device such as a hard disk drive. Some of such image forming apparatuses have a function to temporarily store a received electronic document in the storage device, not automatically outputting the received electronic document onto a recording medium such as paper. That is to say, some image forming apparatuses can function as electronic document management devices.
In general, such an electronic document management device (image forming apparatus) is connected to a network and is shared by a plurality of user terminals via the network. Accordingly, managing the security in relation to the disclosure of the stored electronic document is critical to such an electronic document management device. In one example of conventional security management of electronic documents, a confidential level is assigned to each document file or each folder to restrict the access by users to the file or folder.
Meanwhile, confidential levels of all the constituent elements (such as a drawing, a photograph, and a unit of description) of an electronic document may not necessarily be the same. That is to say, some elements have low confidential levels allowing the elements to be disclosed to all users, while other elements have high confidential levels allowing the elements to be disclosed to only limited users. With this construction, the confidential level of the whole electronic document should be the same as the highest confidential level for the constituent elements. In this case, however, the elements with the low confidential levels, which can be disclosed to all users, are not disclosed. This is problematic from the viewpoint of using electronic documents effectively.
One may think that the problem would be solved if a worker selects constituent elements with low confidential levels among those of an original electronic document, creates another electronic document by the selected elements, and assigns a low confidential level to the newly created electronic document. However, it takes a lot of effort for the worker to create an electronic document for each confidential level.
Japanese Patent Application Publication No. 2001-325249 discloses a document management device aimed to solve the above-described problem. The document management device of this publication sets confidential levels in units of constituent elements of the electronic documents. When a user attempts to access a document, the document management device compares the confidential level (access-right level) of the user with the confidential levels of each constituent element, and judges, for each constituent element, whether or not the constituent element can be disclosed to the user. The document management device then discloses an electronic document to the user by printing or the like, after replacing contents of the constituent elements, which were judged not to be disclosed to the user, with turned letters or the like.
With the above-described construction, the worker need not create an electronic document for each confidential level, realizing an effective use of electronic documents.
However, the document management device disclosed in Japanese Patent Application Publication No. 2001-325249 still has the following problem.
Suppose that User H has a high-level access right while User L has a low-level access right, and these two people are discussing business over phone while respectively seeing electronic documents created from one source stored in the document management device. In this case, the entire document is disclosed to User H, whereas only part of the document is disclosed to User L, with the remaining part concealed. When this happens, User H cannot know which part of the document is visible to User L, and thus may accidentally disclose some contents of the turned-letter portion (namely, a portion having high confidential level). This may result in leakage of the confidential information. Such an occurrence would be prevented if User H has the same electronic document as disclosed to User L. However, to realize it, User H might request User L to send the electronic document to User H, for example. This is inconvenient.